On Thu, Jun 01, 2023 at 01:17:08PM +0800, Heng Qi wrote: > On Thu, Jun 01, 2023 at 12:30:30AM -0400, Michael S. Tsirkin wrote: > > On Tue, May 30, 2023 at 03:40:18PM -0400, Michael S. Tsirkin wrote: > > > On Fri, May 26, 2023 at 04:04:18PM +0800, Heng Qi wrote: > > > > > > > > > > > > 在 2023/5/23 上午11:58, Heng Qi 写道: > > > > > On Mon, May 22, 2023 at 03:19:16PM -0400, Michael S. Tsirkin wrote: > > > > > > On Mon, May 22, 2023 at 01:02:36PM +0800, Heng Qi wrote: > > > > > > > 1. Currently, a received encapsulated packet has an outer and an > > > > > > > inner header, but > > > > > > > the virtio device is unable to calculate the hash for the inner > > > > > > > header. The same > > > > > > > flow can traverse through different tunnels, resulting in the > > > > > > > encapsulated > > > > > > > packets being spread across multiple receive queues (refer to the > > > > > > > figure below). > > > > > > > However, in certain scenarios, we may need to direct these > > > > > > > encapsulated packets of > > > > > > > the same flow to a single receive queue. This facilitates the > > > > > > > processing > > > > > > > of the flow by the same CPU to improve performance (warm caches, > > > > > > > less locking, etc.). > > > > > > > > > > > > > > client1 client2 > > > > > > > | +-------+ | > > > > > > > +------->|tunnels|<--------+ > > > > > > > +-------+ > > > > > > > | | > > > > > > > v v > > > > > > > +-----------------+ > > > > > > > | monitoring host | > > > > > > > +-----------------+ > > > > > > > > > > > > > > To achieve this, the device can calculate a symmetric hash based > > > > > > > on the inner headers > > > > > > > of the same flow. > > > > > > > > > > > > > > 2. For legacy systems, they may lack entropy fields which modern > > > > > > > protocols have in > > > > > > > the outer header, resulting in multiple flows with the same outer > > > > > > > header but > > > > > > > different inner headers being directed to the same receive queue. > > > > > > > This results in > > > > > > > poor receive performance. > > > > > > > > > > > > > > To address this limitation, inner header hash can be used to > > > > > > > enable the device to advertise > > > > > > > the capability to calculate the hash for the inner packet, > > > > > > > regaining better receive performance. > > > > > > > > > > > > > > Signed-off-by: Heng Qi <hen...@linux.alibaba.com> > > > > > > > Reviewed-by: Xuan Zhuo <xuanz...@linux.alibaba.com> > > > > > > > --- > > > > > > > v13->v14: > > > > > > > 1. Move supported_hash_tunnel_types from config space into cvq > > > > > > > command. @Parav Pandit > > > > > > > 2. Rebase to master branch. > > > > > > > 3. Some minor modifications. > > > > > > So, I proposed adding a "generic UDP tunnel" option which simply > > > > > > uses UDP source > > > > > > port for hash. I think it will help us not having to chaise future > > > > > > tunnels as > > > > > > more and more are added. > > > > > I agree, but I thought we'd do this in another thread, sorry. > > > > > Following your suggestion, we should add a field similar to > > > > > \field{generic_udp_tunnel_option} in the > > > > > virtnet_hash_tunnel_config_set > > > > > structure. > > > > > > > > > > \field{generic_udp_tunnel_option} should be 0, 1 or 2. > > > > > > > > > > \field{hash_tunnel_types} is still useful, but for more general > > > > > purpose we need > > > > > to use it together with \field{generic_udp_tunnel_option}. > > > > > > > > > > When \field{generic_udp_tunnel_option} is 0, all tunneling protocols > > > > > included in > > > > > \field{hash_tunnel_types} use the inner header for hashing. For other > > > > > tunnel > > > > > protocols not included in \field{hash_tunnel_types}, the hash is > > > > > calculated as if > > > > > VIRTIO_NET_F_TUNNEL_HASH is not negotiated. > > > > > > > > > > When \field{generic_udp_tunnel_option} is 1, all tunneling protocols > > > > > included in > > > > > \field{hash_tunnel_types} use the inner header for hashing. For other > > > > > tunnel > > > > > protocols not included in \field{hash_tunnel_types}, if their outer > > > > > headers are > > > > > based on UDP protocol, the device use the outer UDP source port for > > > > > hashing. > > > > > For the rest of the tunnel protocols, the hash is calculated as if > > > > > VIRTIO_NET_F_TUNNEL_HASH > > > > > was not negotiated. > > > > > > > > > > When \field{generic_udp_tunnel_option} is 2, for all UDP tunneling > > > > > protocols, > > > > > the outer udp source port is used for hashing, otherwise if the > > > > > tunneling protocol > > > > > is included in \field{hash_tunnel_types}, the inner header is used > > > > > for hashing. > > > > > For the rest of the tunnel protocols, the hash is calculated as if > > > > > VIRTIO_NET_F_TUNNEL_HASH > > > > > was not negotiated. > > > > > > > > > > And for this option, we need to add a reminder: > > > > > Although the \field{generic_udp_tunnel_option} helps us adapt to more > > > > > new > > > > > tunneling protocols, it is still an unreliable option, especially for > > > > > tunneling protocols that use "SHOULD" "Recommended" in their own > > > > > specifications, because it means the udp source port does not > > > > > always fully identify a stream. > > > > > > > > > > > > > Hi, Michael. > > > > > > > > Do you agree with this plan? Please let me know if you have any > > > > comments.:) > > > > > > > > If there are no comments, I can start a new version to make progress. > > > > > > > > Thanks. > > > > > > How are "tunneling protocols" defined though? > > > > > > Maybe pass a mask of destination UDP ports for which this applies? > > > > > > Then we don't need options, if port is set in mask then > > > generic udp tunnel inner hash applies. If port is not set then > > > hash is calculated in some other way, including > > > one of tunnel specific flags. > > > > I admit this is pretty complex though. As an intermediate step > > I can see two other options: > > - just do this for all UDP packets assuming most traffic is encapsulated > > This is a bit crude, but it does simplify the complexity of device > implementations. > > > - assume that the list of protocols is configured in the NIC > > by other means (e.g. hard-coded, or we can add an admin command for this) > > Other means also means hardcoding, because we always need to know what > the "new tunnel type" is, otherwise the driver can't understand it. > Assuming we don't use any hard-coded tunnel types for the > VIRTIO_NET_F_TUNNEL_HASH feature, then we use the GET command to get the > tunnel types supported by the device before we intend to use the > inner header hashing capabilities. But if we don't do mappings for > these codes, the driver can't understand what the device returns. Then > we need to hardcode it...
Yes, if we have a GET command that will need a bitmap anyway, so let's just set a bitmap with a command. > > So I tend to dst port mask, or generic option (set to 1 to use source > port for all UDP packets). > Thanks. Makes sense, and I don't think we need both options. > > > > Thoghts? > > > > > > > > > > > > > I also suggested dropping some tunnels which are less common and > > > > > > where > > > > > > the specification is unambiguous enough that source port should > > > > > > include > > > > > > inner hash. > > > > > OK, I'll re-screen and update the tunneling protocols we already > > > > > include > > > > > (e.g. remove STT since it fits what you said). > > > > > > > > > > Thanks. > > > > > > > > > > --------------------------------------------------------------------- > > > > > To unsubscribe, e-mail: virtio-dev-unsubscr...@lists.oasis-open.org > > > > > For additional commands, e-mail: virtio-dev-h...@lists.oasis-open.org --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscr...@lists.oasis-open.org For additional commands, e-mail: virtio-dev-h...@lists.oasis-open.org